title: Elucidation of the distal convoluted tubule transcriptome identifies new candidate genes involved in renal Mg(2+) handling.
abstract: The kidney plays a key role in the maintenance of Mg(2+) homeostasis. Specifically, the distal convoluted tubule (DCT) is instrumental in the fine-tuning of renal Mg(2+) handling. In recent years, hereditary Mg(2+) transport disorders have helped to identify important players in DCT Mg(2+) homeostasis. Nevertheless, several proteins involved in DCT-mediated Mg(2+) reabsorption remain to be discovered, and a full expression profile of this complex nephron segment may facilitate the discovery of new Mg(2+)-related genes. Here, we report Mg(2+)-sensitive expression of the DCT transcriptome. To this end, transgenic mice expressing enhanced green fluorescent protein under a DCT-specific parvalbumin promoter were subjected to Mg(2+)-deficient or Mg(2+)-enriched diets. Subsequently, the Complex Object Parametric Analyzer and Sorter allowed, for the first time, isolation of enhanced green fluorescent protein-positive DCT cells. RNA extracts thereof were analyzed by DNA microarrays comparing high versus low Mg(2+) to identify Mg(2+) regulatory genes. Based on statistical significance and a fold change of at least 2, 46 genes showed differential expression. Several known magnesiotropic genes, such as transient receptor potential cation channel, subfamily M, member 6 (Trpm6), and Parvalbumin, were upregulated under low dietary Mg(2+). Moreover, new genes were identified that are potentially involved in renal Mg(2+) handling. To confirm that the selected candidate genes were regulated by dietary Mg(2+) availability, the expression levels of solute carrier family 41, member 3 (Slc41a3), pterin-4 α-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor-1α (Pcbd1), TBC1 domain family, member 4 (Tbc1d4), and uromodulin (Umod) were determined by RT-PCR analysis. Indeed, all four genes show significant upregulation in the DCT of mice fed a Mg(2+)-deficient diet. By elucidating the Mg(2+)-sensitive DCT transcriptome, new candidate genes in renal Mg(2+) handling have been identified.
authors.affiliation: Dept. of Physiology (286 Radboud Univ. Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, PO Box 9101, Nijmegen 6500 HB, The Netherlands. J.Hoenderop@fysiol.umcn.nl.
authors.forename: Jeroen H F
authors.initials: JH
authors.lastname: de Baaij
authors.forename: Marian J
authors.initials: MJ
authors.lastname: Groot Koerkamp
authors.forename: Marla
authors.initials: M
authors.lastname: Lavrijsen
authors.forename: Femke
authors.initials: F
authors.lastname: van Zeeland
authors.forename: Hans
authors.initials: H
authors.lastname: Meijer
authors.forename: Frank C P
authors.initials: FC
authors.lastname: Holstege
authors.forename: René J M
authors.initials: RJ
authors.lastname: Bindels
authors.forename: Joost G J
authors.initials: JG
authors.lastname: Hoenderop
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000235:genetics*; D002352:Carrier Proteins / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology*; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009399:Nephrons / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D008274:Magnesium
keywords: Complex Object Parametric Analyzer and Sorter; distal convoluted tubule; gene expression microarray; hypomagnesemia; magnesium homeostasis